Insulating materials and process of manufacture of same



Patented June 17, 1930 UNITED", STATES PATENT OFFICE WALTER L. STEFFENS,OF WYOMING, OHIO, ASSIGNOR'TO THE PHILIP CAREY MANU- FACTURING COMPANY,CORPORATION OF OHIO D INSULATING MATERIALS AN D PROCESS OF MANUFACTUREOF SAME No Drawing.

factory for'insulating material as has heretofore occurred when what iscommonly known as 85% magnesia covering has been used. My improvedinsulating material has a low rate of heat transmission, has highinsulating value, is mechanically strong, is

light in weight, and when manufactured has a non-powderin refractorysurface and can be manufactured at a comparatively low cost. In thepreferred process of manufacture of my insulating material I first moulda block composed of a major proportion of carbonate of magnesia,preferably about and a minor proportion of asbestos. This block isdried. After drying it is heat treated to shrink same and is then milledto form and size. For some purposes when the material is to be used onsurfaces where it willbe subjected to. a comparatively high temperaturei.'e., 750 to 800 degrees F., I have found it desirable to subject it toheat treatment at a temperature approximately the temperature to whichit is to be subjected in use. When this block has been formed todesired'size and. form I preferably treat it to a solution of sodiumsilicate by dipping it ina bath so as to impregnate it with the sodiumsilicate. The preferred impregnating solution to obtain the resultdesired is a solution consisting of six (6) parts of water to one (1)part 40 B. sodium silicate. Such a solution enables me to by treatingthe carbonate magnesia asbestos block for a period of about one and onehalf minutes to impregnate a block of about 1 to 2 inches thick with therequisite amount of sodium silicate so as to Application filed April 8,1925. Serial No. 21.725.

form an insulating material of desired strength and other qualities setforth above. I

A solution containing appreciably more sodium silicate and less water ormore water and less sodium silicate would not give the properimpregnation. By this I do not mean that the solution could not bevaried slightly as to the relative quantities but no latitude can beallowed'beyond the limits of the formula stated. Insulating materialdiffers in thickness due to the purpose for which it is to be used and Ihave found that to get a satisfactory impregnation it is preferable totreat the material if 1 inch thick to the impregnation treatment forabout 1 minute, if 1 inches or 2 inches thick I treat it for a minuteand a half and greater thicknesses in like proportions. After the sodiumsilicate treatment the blocks are air dried at normal room tem eratureand then they are subjected to furt er drying in a heated room. I havefound that this method of drying after impregnation enables me to makethe material without danger of warp ing as generally occurs Where it isimmediately submitted to the action of heat before the excess moisturehas dried out. In the process of manufacture of my insulation materialthe order of treatment after moulding and drying the block may be variedby either heat treating, milling and then impregnating, or b heattreating, impregnating and then milhng, or by any variation in'the orderof the three steps of heat treating, milling and impregnating, withoutdeparting from my invention. Wherever in the speci cation or claims Ihave used the expression block ll would have it understood as meaning apiece of insulating material, whether in the form of a cylindrical pipecovering, a fitting for a valve, what is known as lagging or whateverother form of moulded insulating material.

Claims- 1. In the manufacture of insulating mate-' eat um silicate, thefluidity and strength of the solution and the duration of the treatmentbeing such that the block is completely 1m: regnated with said solutionand thereafter hardened substantially throughout.

2. In the manufacture of insulating mate rial, the process whichcomprises forming a block composed of a major pro rtion of magnesia anda minor proportion 0 a suitable fibrous binder, and sub]ecting theblock'to the action of an aqueous solution of sodium silicate containingsix (6) and one 1) part of sodium silicate, the duration of thetreatment being such that said block is completely impregnated with saidsolution and thereafter hardened substantially throughout.

3. In the manufacture of insulating material, the process whichcomprises forming a blockcomposed of a major proportion of magnesia anda minor proportion of a suitable fibrous binder, soaln'ng the block withan aqueous solution of sodium silicate for at least one minute in thecase of a block one inch thick and prolonging the soaking in the case ofblocks of greater thickness for at least one-half minute for each inchof thickness or fraction thereof in excess of one inch, the fluidity andstren h of said solution being such that said b ock is completelyimpregnated with said solution and thereafter hardened substantiallythroughout.

4. In the manufacture of insulating material, the process whichcomprises forming a.

,block composed of a major proportion of magnesia and a minor proportionof a suitable fibrous binder, drying said block, milling said block,soaking said block with an aqueous solution of sodium silicate, airdrying said block, and then heat treating the same, the fluidity andstrength of said solution and the duration of the soaking being suchthat said block is completely impregnated, and the temperature of saidheat treatment being at least as great as that to which said block willbe s'ub ected in actual use.

5. In the manufacture of insulating material, the process whichcomprises forming a block com osed of approximately eighty-five per cent85%) of magnesia and approximately fifteen per cent (15%) of asbestos,drying said block, milling said block, soakmg said block with an aqueoussolution of sodium silicate containing six (6) parts of water and one(1) part of sodium silicate, such soaking being continued for at leastone minute in the case of a block one inch thick and bemg prolonged, inthe case of blocks of greater thickness, for at least one-half minutefor each inch of thickness or fraction thereof in excess of one inch,then air drying sa d block and heat treating the same at 'a temperaturebetween 500 and 800 F., the fluidity and strength of said'solution andthe duration of the treatment with said solution parts of water

